title: Basal-like immunophenotype markers and prognosis in early breast cancer.
abstract: OBJECTIVE
  Basal-like breast cancer is a distinct group of tumors with heterogeneous behavior, and not all have a poor prognosis. The present study analyzed the prevalence and prognosis of early basal-like breast cancer.
  
  
  METHODS
  A total of 112 patients with stage I and II breast cancer were retrospectively analyzed using immunohistochemical stains for estrogen receptor, progesterone receptor, HER2, cytokeratin 5/6 and epidermal growth factor receptor. Basal-like tumors were defined as being estrogen receptor, progesterone receptor and HER2 negative and cytokeratin 5/6 and/or epidermal growth factor receptor positive.
  
  
  RESULTS
  Of the 112 cases, respectively 13 (11.6%) were basal-like, 77 (68.8%) luminal A or B, 13 (11.6%) HER2 positive and 9 (8%) undefined. In basal-like tumors, epidermal growth factor receptor and cytokeratin 5/6 expression was positive in 5 patients (38.5%) and 12 patients (92%), respectively. There was no significant correlation between basal-like breast cancer and age (P = 0.207), lymph node status (P = 1.0) or clinical stage (P = 0.53). Among all tested biomarkers, positivity was found in 81 (72.3%) for estrogen receptor, 13 (11.6%) for HER2, 11 (9.8%) for epidermal growth factor receptor and 36 (32.1%) for cytokeratin 5/6. Epidermal growth factor receptor expression was significantly correlated with estrogen receptor-negative (P = 0.01) and HER2-positive (P = 0.02) tumors. During a median follow-up of 81 months, there were 26 (23%) disease relapses and 12 (10.7%) deaths. No significant difference relating to disease-free survival and overall survival was noted between basal-like breast cancer and subtypes luminal A and B, HER2 positive and undefined.
  
  
  CONCLUSIONS
  The addition of cytokeratin 5/6 and epidermal growth factor receptor defines a small subgroup of patients with basal-like tumors. In a population with early breast cancer, basal-like tumors did not have a prognosis different from the other subtypes. Neither was there a significant association with clinicopathological features. The high frequency of epidermal growth factor receptor positivity in estrogen receptor-negative and HER2-positive tumors represents a potential target in clinical trials.
authors.affiliation: Faculty of Medicine, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Lina
authors.initials: L
authors.lastname: Cassol
authors.forename: Marcia
authors.initials: M
authors.lastname: Silveira Graudenz
authors.forename: Alice
authors.initials: A
authors.lastname: Zelmanowicz
authors.forename: Anna
authors.initials: A
authors.lastname: Cancela
authors.forename: Gustavo
authors.initials: G
authors.lastname: Werutsky
authors.forename: Rodrigo Kraft
authors.initials: RK
authors.lastname: Rovere
authors.forename: Bernardo
authors.initials: B
authors.lastname: Garicochea
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000737:chemistry* / Q000401:mortality / Q000473:pathology*; D002280:Basal Cell Carcinoma / Q000737:chemistry* / Q000401:mortality / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000737:chemistry* / Q000473:pathology; D018275:Carcinoma, Lobular / Q000737:chemistry* / Q000473:pathology; D066246:ErbB Receptors / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D053555:Keratin-5 / Q000032:analysis; D053553:Keratin-6 / Q000032:analysis; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000737:chemistry / Q000473:pathology; D011237:Predictive Value of Tests; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012008:Recurrence
chemical_list: D014408:Biomarkers, Tumor; D066246:ErbB Receptors; D053555:Keratin-5; D053553:Keratin-6; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone